Method for modifying a control software of an automation system

A method for modifying a control software of an automation system comprising a controller and a plurality of subscribers,

• wherein the subscribers are connected to the controller via a data bus and communicate via a data exchange,
• wherein the data bus is configured as a field bus, wherein at least one of the subscribers is a software subscriber for modifying a control software of the controller,
• wherein data communication is realized by sending and receiving data between the controller and the subscribers, or between the subscribers,
• wherein sending and receiving of data by the subscribers is performed via a data telegram in which each respective subscriber reads first data from the data telegram and inserts second data into the data telegram, wherein the subscribers each have a receiving unit and a transmitting unit configured for receiving and transmitting the data telegram;
• wherein the software subscriber is configured as a software terminal,
• wherein the subscribers are configured as subscriber terminals,
• wherein the software terminal and the subscriber terminals are further configured as bus terminals,
• wherein the subscriber terminals and the software terminal are connected to one another via an internal bus line, and wherein the subscriber terminals and the software terminal are each latched over a corresponding mounting rail and form a terminal system, and
• wherein the software subscriber comprises a memory unit on which at least one modification instruction for modifying the control software is stored, wherein the at least one modification instruction comprises a part of the control software to be modified and/or an additional part of the control software;
• the method comprising:
• sending an individual query message by the controller to the software subscriber to query the at least one modification instruction to modify the control software in a first query step;
• sending a response message by the software subscriber to the controller for providing the at least one modification instruction to modify the control software in a first response step;
• verifying the at least one modification instruction for modifying the control software by the controller as to whether the modification instruction is compatible with the control software in a verification step;
• modifying the control software in accordance with the modification instruction and implementing the modification of the modification instruction in the existing control software by the controller in a modification step if the modification instruction is compatible with the control software;
• and
• discarding of the modification instruction by the controller in a discard step if the modification instruction is incompatible with the control software, wherein modifying the control software according to the modification step comprises including at least one additional subscriber to the plurality of subscribers that is not the software subscriber in the data bus of the automation system, wherein the software terminal serves as an addressing zero point with respect to an additional device associated with the additional subscriber terminal positioned behind the software subscriber in the terminal system, and wherein the controller addresses the additional device associated with the additional subscriber terminal by counting positions in the terminal system between the position of the software terminal and the position of the additional subscriber terminal in the terminal system.